Device and method for protecting medical devices during a coating process

ABSTRACT

Methods and devices for protecting and/or coating medical devices are disclosed. In one embodiment, a method is disclosed that includes surrounding a medical device with a cage, the medical device having a surface. The method further includes attaching the medical device to the cage with at least one securement, suspending the medical device in an air stream, the air stream substantially devoid of suspending particles, and coating at least a portion of said surface of said suspended medical device with a first coating material.

[0001] This application is a continuation-in-part of pending applicationSer. No. 09/551,614, filed Apr. 17, 2000, which is acontinuation-in-part of pending application Ser. No. 09/293,994, filedApr. 19, 1999.

FIELD OF THE INVENTION

[0002] The present invention relates to coated medical devices, and moreparticularly to a device and method for protecting medical devicesduring a coating process.

BACKGROUND OF THE INVENTION

[0003] It is often beneficial to coat medical devices so that thesurfaces of such devices have desired properties or effects. Forexample, it is useful to coat medical devices to provide for thelocalized delivery of therapeutic agents to target locations within thebody, such as to treat localized disease (e.g., heart disease) oroccluded body lumens. Such localized drug delivery avoids the problemsof systemic drug administration, which may be accompanied by unwantedeffects on parts of the body which are not to be treated, or becausetreatment of the afflicted part of the body requires a highconcentration of therapeutic agent that may not be achievable bysystemic administration. Localized drug delivery is achieved, forexample, by coating balloon catheters, stents and the like with thetherapeutic agent to be locally delivered. The coating on medicaldevices may provide for controlled release, which includes long-term orsustained release, of a bioactive material.

[0004] Aside from facilitating localized drug delivery, medical devicesare coated with materials to provide beneficial surface properties. Forexample, medical devices are often coated with radiopaque materials toallow for fluoroscopic visualization during placement in the body. It isalso useful to coat certain devices to achieve enhanced biocompatibilityand to improve surface properties such as lubriciousness.

[0005] Conventionally, coatings have been applied to medical devices byprocesses such as dipping, spraying, vapor deposition, plasmapolymerization, and electrodeposition. Although these processes havebeen used to produce satisfactory coatings, there are numerous potentialdrawbacks associated therewith. For example, it is often difficult toachieve coatings of uniform thicknesses, both on individual parts and onbatches of parts. Also, many of these conventional coating processesrequire that the coated part be held during coating, resulting indefects such as bare spots where the part was held and thus requiringsubsequent coating steps. Further, many conventional processes requiremultiple coating steps or stages for the application of a second coatingmaterial, or to allow for drying between coating steps or after thefinal coating step.

[0006] There is, therefore, a need for a cost-effective method ofcoating medical devices that results in uniform, defect-free coatingsand uniform drug doses per unit device. The method would allow for amultiple stage coating in order to apply a bioactive material that maybe environmentally sensitive, e.g., due to heat and light (includingultra-violet) exposure and due to degradation of the bioactive materialdue to process-related forces (e.g., shear). The method would thus allowfor better control of the sensitivity of the bioactive material andreduce any potential degradation due to environmental issues. The methodwould also reduce variations in the coating properties.

SUMMARY OF THE INVENTION

[0007] In one aspect, the present invention relates to methods forcoating at least a portion of a medical device which is used, at leastin part, to penetrate the body of a patient. In one embodiment, themethod comprises the steps of suspending the medical device in an airstream that is substantially devoid of suspending particles andintroducing a coating material into the air stream such that the coatingmaterial is dispersed therein and coats at least a portion of themedical device. This process is used to apply one or more coatingmaterials, simultaneously or in sequence. In certain embodiments of theinvention, the coating materials include therapeutic agents, polymericmaterials, and sugars, waxes, and fats. A coating substance that iscomprised of suspension particles may be utilized that are fused to thesurface of the medical device by a coating solution.

[0008] In another embodiment of the present invention, the medicaldevices are suspended in an air stream substantially devoid ofsuspending particles and a coating apparatus coats at least a portion ofthe medical device with a coating material while the medical devices aresuspended in the air stream. The coating apparatus may include a devicethat utilizes any number of alternative coating techniques for coatingthe medical devices.

[0009] In another aspect, the present invention relates to coatedmedical devices made by the method of the invention.

[0010] One advantage of the present invention is that it provides coatedmedical devices with uniform coating thicknesses and mechanicalproperties and minimal contaminants.

[0011] Another advantage of the present invention is that it allowssimultaneous coating of multiple numbers of medical devices at the sametime, thus leading to higher process efficiency.

[0012] Another advantage of the present invention is that it does notrequire that the medical device be held during the coating process,thereby eliminating bare spots and the need for subsequent coating stepsto coat such bare spots.

[0013] Another advantage of the present invention is that it provides amethod for coating medical devices by coating materials that areotherwise difficult to use, such as incompatible, insoluble/suspension,or unstable coating solutions.

[0014] Another advantage of the present invention is that it reduceshuman exposure to materials used in conventional coating processes suchas solvents, polymers, drugs, and the like.

[0015] Another advantage of the present invention is that it allows forthe application of multiple coating materials to numerous medicaldevices in a single batch coating process.

[0016] Yet another advantage of the present invention is that itprovides a method for coating a medical device that results in a uniformdrug dose per unit device.

[0017] In another aspect, the present invention relates to devices andmethods for protecting medical devices from damage during a coatingprocess. In one embodiment, a protective device includes anopen-structure solvent-resistant cage non-contactably surrounding amedical device, the medical device having a plurality of contact points.The protective device also includes a plurality of solvent-resistantsecurements, each solvent-resistant securement from said plurality ofsolvent-resistant securements attached to said cage and in contact withat least one of said plurality of contact points of the medical device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a cross-sectional view of an apparatus for coatingmedical devices in accordance with a first embodiment of the presentinvention.

[0019]FIG. 2 is a cross-sectional view of an apparatus for coatingmedical devices in accordance with a second embodiment of the presentinvention.

[0020]FIG. 3 illustrates a plasma coating apparatus in accordance withthe principles of the present invention.

[0021]FIG. 4 is a perspective view of a protective device in accordancewith a third embodiment of the present invention.

[0022]FIG. 5 is a perspective view of a protective device in accordancewith another embodiment of the present invention.

DETAILED DESCRIPTION

[0023] The present invention provides methods for coating medicaldevices, and devices thereby produced. By using air suspension to coatmedical devices, the methods of the present invention result in coatingshaving minimal defects and uniform thicknesses and mechanicalproperties. Further, the methods of the present invention are timeefficient and cost effective because they facilitate the uniform coatingof numerous medical devices in a single batch.

[0024] Whereas the present invention allows multiple medical devices tobe coated as a batch, the present invention is not limited to onlycoating medical devices in batches, i.e., coating a group of devices inone batch process followed by coating a second group of devices in asecond batch process. The methods and apparatuses of the presentinvention can be utilize to continuously run medical devices through theapparatuses such that the process does not have to be started andstopped for coating the medical devices in batches. The medical devicescan be run through a continuous process.

[0025] In all embodiments of the present invention, single or multiplecoating materials are applied to medical devices by suspending themedical devices in an air stream and coating at least a portion of themedical device. As used herein, “air stream” refers to a stream of anysuitable gas, such as air, nitrogen, argon and combinations thereof. Theair stream is said to be “substantially devoid of suspending particles”,i.e., particles are not utilized to suspend the medical devices withinthe air stream. The air stream itself suspends the medical devices. Anynon-coating particles (i. e., particles that do not become at leastpartially part of the coating materials) that may be present in the airstream do not materially provide for suspending the medical devices.Particles might be added to the air stream to enhance the coatingprocess, e.g., a polishing media and/or electrostatic inhibitors in lowratios, however, these added particles are not used to suspend thearticles to be coated. Thus, the air stream, since it is substantiallydevoid of suspending particles and only requires the air itself in theair stream to suspend the medical devices, may be termed a homogenoussuspending air stream. As used herein, “suspending” the medical deviceshall refer to a process whereby the medical device is situated withinthe flow of an air stream and may be moving within the air stream whileunsupported by any external means.

[0026] The medical devices used in conjunction with the presentinvention include any device amenable to the coating processes describedherein. The medical device, or portion of the medical device, to becoated or surface modified may be made of metal, polymers, ceramics,composites or combinations thereof, and for example, may be coated withone or more of these materials. Whereas the present invention isdescribed herein with specific reference to a vascular stent, othermedical devices within the scope of the present invention include anydevices which are used, at least in part, to penetrate the body of apatient. Examples include implantable devices such as catheters, needleinjection catheters, blood clot filters, vascular grafts, stent grafts,biliary stents, colonic stents, bronchial/pulmonary stents, esophagealstents, ureteral stents, aneurysm filling coils and other coiled coildevices, trans myocardial revascularization (“TMR”) devices,percutaneous myocardial revascularization (“PMR”) devices etc., as areknown in the art, as well as devices such as hypodermic needles, softtissue clips, holding devices, and other types of medically usefulneedles and closures. Any exposed surface of these medical devices maybe coated with the methods and apparatuses of the present inventionincluding, for example, the inside exposed surface and the outsideexposed surface of a tubular medical device which is open at both ends.

[0027] The coating materials used in conjunction with the presentinvention are any desired, suitable substances. In some embodiments, thecoating materials comprise therapeutic agents, applied to the medicaldevices alone or in combination with solvents in which the therapeuticagents are at least partially soluble or dispersible or emulsified,and/or in combination with polymeric materials as solutions,dispersions, suspensions, latices, etc. The terms “therapeutic agents”and “drugs” are used interchangeably herein and include pharmaceuticallyactive compounds, nucleic acids with and without carrier vectors such aslipids, compacting agents (such as histones), virus, polymers, proteins,and the like, with or without targeting sequences. The coating on themedical devices may provide for controlled release, which includeslong-term or sustained release, of a bioactive material.

[0028] Specific examples of therapeutic or bioactive agents used inconjunction with the present invention include, for example,pharmaceutically active compounds, proteins, oligonucleotides,ribozymes, anti-sense genes, DNA compacting agents, gene/vector systems(i.e., anything that allows for the uptake and expression of nucleicacids), nucleic acids (including, for example, recombinant nucleicacids; naked DNA, cDNA, RNA; genomic DNA, cDNA or RNA in anon-infectious vector or in a viral vector which may have attachedpeptide targeting sequences; antisense nucleic acid (RNA or DNA); andDNA chimeras which include gene sequences and encoding for ferryproteins such as membrane translocating sequences (“MTS”) and herpessimplex virus-1 (“VP22”)), and viral, liposomes and cationic polymersthat are selected from a number of types depending on the desiredapplication. For example, biologically active solutes includeanti-thrombogenic agents such as heparin, heparin derivatives,urokinase, and PPACK (dextrophenylalanine proline argininechloromethylketone); prostaglandins, prostacyclins/prostacyclin analogs;antioxidants such as probucol and retinoic acid; angiogenic andanti-angiogenic agents; agents blocking smooth muscle cell proliferationsuch as rapamycin, angiopeptin, and monoclonal antibodies capable ofblocking smooth muscle cell proliferation; anti-inflammatory agents suchas dexamethasone, prednisolone, corticosterone, budesonide, estrogen,sulfasalazine, acetyl salicylic acid, and mesalamine, lipoxygenaseinhibitors; calcium entry blockers such as verapamil, diltiazem andnifedipine; antineoplastic/antiproliferative/anti-mitotic agents such aspaclitaxel, 5-fluorouracil, methotrexate, doxorubicin, daunorubicin,cyclosporine, cisplatin, vinblastine, vincristine, colchicine,epothilones, endostatin, angiostatin, Squalamine, and thymidine kinaseinhibitors; L-arginine; antimicrobials such as triclosan,cephalosporins, aminoglycosides, and nitorfurantoin; anesthetic agentssuch as lidocaine, bupivacaine, and ropivacaine; nitric oxide (NO)donors such as lisidomine, molsidomine, NO-protein adducts,NO-polysaccharide adducts, polymeric or oligomeric NO adducts orchemical complexes; anti-coagulants such as D-Phe-Pro-Arg chloromethylketone, an RGD peptide-containing compound, heparin, antithrombincompounds, platelet receptor antagonists, anti-thrombin antibodies,anti-platelet receptor antibodies, enoxaparin, hirudin, Warafin sodium,Dicumarol, aspirin, prostaglandin inhibitors, platelet inhibitors andtick antiplatelet factors; interleukins, interferons, and free radicalscavengers; vascular cell growth promoters such as growth factors,growth factor receptor antagonists, transcriptional activators, andtranslational promotors; vascular cell growth inhibitors such as growthfactor inhibitors (e.g., PDGF inhibitor - Trapidil), growth factorreceptor antagonists, transcriptional repressors, translationalrepressors, replication inhibitors, inhibitory antibodies, antibodiesdirected against growth factors, bifunctional molecules consisting of agrowth factor and a cytotoxin, bifunctional molecules consisting of anantibody and a cytotoxin; Tyrosine kinase inhibitors, chymaseinhibitors, e.g., Tranilast, ACE inhibitors, e.g., Enalapril, MMPinhibitors, (e.g., Ilomastat, Metastat), GP IIb/IIIa inhibitors (e.g.,Intergrilin, abciximab), seratonin antagnonist, and 5-HT uptakeinhibitors; cholesterol-lowering agents; vasodilating agents; agentswhich interfere with endogeneus vascoactive mechanisms; survival geneswhich protect against cell death, such as anti-apoptotic Bcl-2 familyfactors and Akt kinase; and combinations thereof, and beta blockers.These and other compounds may be added to a coating solution, includinga coating solution that includes a polymer, using similar methods androutinely tested as set forth in the specification. Any modificationsare routinely made by one skilled in the art.

[0029] Polynucleotide sequences useful in practice of the inventioninclude DNA or RNA sequences having a therapeutic effect after beingtaken up by a cell. Examples of therapeutic polynucleotides includeanti-sense DNA and RNA; DNA coding for an anti-sense RNA; or DNA codingfor tRNA or rRNA to replace defective or deficient endogenous molecules.The polynucleotides of the invention can also code for therapeuticproteins or polypeptides. A polypeptide is understood to be anytranslation product of a polynucleotide regardless of size, and whetherglycosylated or not. Therapeutic proteins and polypeptides include as aprimary example, those proteins or polypeptides that can compensate fordefective or deficient species in an animal, or those that act throughtoxic effects to limit or remove harmful cells from the body. Inaddition, the polypeptides or proteins that can be incorporated into thepolymer coating, or whose DNA can be incorporated, include withoutlimitation, angiogenic factors and other molecules competent to induceangiogenesis, including acidic and basic fibroblast growth factors,vascular endothelial growth factor, hif-1, epidermal growth factor,transforming growth factor α and β, platelet-derived endothelial growthfactor, platelet-derived growth factor, tumor necrosis factor α,hepatocyte growth factor and insulin like growth factor; growth factors;cell cycle inhibitors including CDK inhibitors; anti-restenosis agents,including p15, p16, p18, p19, p21, p27, p53, p57, Rb, nFkB and E2Fdecoys, thymidine kinase (“TK”) and combinations thereof and otheragents useful for interfering with cell proliferation, including agentsfor treating malignancies; and combinations thereof. Still other usefulfactors, which can be provided as polypeptides or as DNA encoding thesepolypeptides, include monocyte chemoattractant protein (“MCP-1”), andthe family BMP-3, BMP-4, BMP-5, BMP-6 (Vgr-1), BMP-7 (OP-1), BMP-8,BMP-9, BMP-10, BMP-11, BMP-12, BMP-13, BMP-14, BMP-15, and BMP-16.Currently preferred BMPs are any of BMP-2, BMP-3, BMP-4, BMP-5, BMP-6and BMP-7. These dimeric proteins can be provided as homodimers,heterodimers, or combinations thereof, alone or together with othermolecules. Alternatively, or in addition, molecules capable of inducingan upstream or downstream effect of a BMP can be provided. Suchmolecules include any of the “hedgehog” proteins, or the DNA's encodingthem.

[0030] Coating materials other than therapeutic agents include, forexample, polymeric materials, sugars, waxes, and fats, applied alone orin combination with therapeutic agents, and monomers that arecross-linked or polymerized. Such coating materials are applied in theform of, for example, powders, solutions, dispersions, suspensions,and/or emulsions of one or more polymers, optionally in aqueous and/ororganic solvents and combinations thereof or optionally as liquid meltsincluding no solvents. When used with therapeutic agents, the polymericmaterials are optionally applied simultaneously with, or in sequence to(either before or after), the therapeutic agents. Such polymericmaterials employed as, for example, primer layers for enhancingsubsequent coating applications (e.g., application of alkanethiols orsulfhydryl-group containing coating solutions to gold-plated devices toenhance adhesion of subsequent layers), layers to control the release oftherapeutic agents (e.g., barrier diffusion polymers to sustain therelease of therapeutic agents, such as hydrophobic polymers; thermalresponsive polymers; pH-responsive polymers such as cellulose acetatephthalate or acrylate-based polymers, hydroxypropyl methylcellulosephthalate, and polyvinyl acetate phthalate), protective layers forunderlying drug layers (e.g., impermeable sealant polymers such asethylcellulose), biodegradable layers, biocompatible layers (e.g.,layers comprising albumin or heparin as blood compatible biopolymers,with or without other hydrophilic biocompatible materials of syntheticor natural origin such as dextrans, cyclodextrins, polyethylene oxide,and polyvinyl pyrrolidone), layers to facilitate device delivery (e.g.,hydrophilic polymers, such as polyvinyl pyrrolidone, polyvinyl alcohol,polyalkylene gylcol (i.e., for example, polyethylene glycol), oracrylate-based polymer/copolymer compositions to provide lubricioushydrophilic surfaces), drug matrix layers (i.e., layers that adhere tothe medical device and have therapeutic agent incorporated therein orthereon for subsequent release into the body), and epoxies.

[0031] When used as a drug matrix layer for localized drug delivery, thepolymer coatings of the present invention comprise any material capableof absorbing, adsorbing, entrapping, or otherwise holding thetherapeutic agent to be delivered. The material is, for example,hydrophilic, hydrophobic, and/or biodegradable, and is preferablyselected from the group consisting of polycarboxylic acids, cellulosicpolymers, gelatin, polyvinylpyrrolidone, maleic anhydride polymers,polyamides, polyvinyl alcohols, polyethylene oxides, glycosaminoglycans,polysaccharides, polyesters, polyurethanes, silicones, polyurea,polyacrylate, polyacrylic acid and copolymers, polyorthoesters,polyanhydrides such as maleic anhydride, polycarbonates, polyethylene,polypropylenes, polylatic acids, polystyrene, natural and syntheticrubbers and elastomers such as polyisobutylene, polyisoprene,polybutadiene, including elastomeric copolymers, such as Kraton®,styrene-isobutylene-styrene (SIBS) copolymers; polyglycolic acids,polycaprolactones, polyhydroxybutyrate valerates, polyacrylamides,polyethers, polysaccharides such as cellulose, starch, dextran andalginates; polypeptides and proteins including gelatin, collagen,albumin, fibrin; copolymers of vinyl monomers such as ethylene vinylacetate (EVA), polyvinyl ethers, polyvinyl aromatics; other materialssuch as cyclodextrins, hyaluronic acid and phosphorylcholines; andmixtures and copolymers thereof. Coatings from polymer dispersions suchas polyurethane dispersions (BAYHDROL, etc.) and acrylic latexdispersions are also within the scope of the present invention.Preferred polymers include polyurethanes; polyacrylic acid as describedin U.S. Pat. No. 5,091,205, the disclosure of which is incorporatedherein by reference; and aqueous coating compositions comprising anaqueous dispersion or emulsion of a polymer having organic acidfunctional groups and a polyfunctional crosslinking agent havingfunctional groups capable of reacting with organic acid groups, asdescribed in U.S. Pat. No. 5,702,754, the disclosure of which isincorporated herein by reference.

[0032] The release rate of drugs from drug matrix layers is largelycontrolled, for example, by variations in the polymer structure andformulation, the diffusion coefficient of the matrix, the solventcomposition, the ratio of drug to polymer, potential chemical reactionsand interactions between drug and polymer, the thickness of the drugadhesion layers and any barrier layers, and the process parameters,e.g., drying, etc. The coating(s) applied by the methods and apparatusesof the present invention may allow for a controlled release rate of acoating substance with the controlled release rate including bothlong-term and/or sustained release.

[0033] Additionally, a coating substance may include suspensionparticles, e.g., a powder. The suspension particles are not utilized forsuspending the medical devices, but rather, are coated onto the medicaldevices. For example, the suspension particles may be fused to thesurface of the medical device by a coating solution.

[0034] The coatings of the present invention are applied such that theyresult in a suitable thickness, depending on the coating material andthe purpose for which the coating(s) is applied. As an example, coatingsapplied for localized drug delivery are typically applied to a thicknessof about 1 to 30 microns, preferably about 2 to 20 microns. Very thincoatings, e.g., of about 100Å, and much thicker coatings, e.g., morethan 30 microns, are also possible. It is also within the scope of thepresent invention to apply multiple layers of the same or differentcoating materials, which may perform identical or different functions(e.g., to provide for biocompatibility, to control drug release, etc.).

[0035] In accordance with a first embodiment of the present invention,medical devices are coated by suspending the medical device in an airstream substantially devoid of suspending particles having a firstcoating material dispersed therein, by any corresponding, suitablemethod. For illustrative purposes only, the first embodiment of theinvention is described with specific reference to the so-called “Wursterprocess” shown in FIG. 1. The Wurster process is described in U.S. Pat.No. 3,253,944, which is incorporated herein by reference. Such a processhas been proposed for use to coat pharmaceutical tablets with waxes(see, e.g., D. M. Jones, “Factors to Consider in Fluid-Bed Processing,”9 Pharm. Tech. 50-62 (1985), and A. M. Mehta, “Scale-Up Considerationsin the Fluid-Bed Process for Controlled-Release Products,” 12 Pharm.Tech. (1988)), but has not been proposed or used to coat medicaldevices.

[0036] As stated above, the first embodiment for an apparatus forcoating medical devices 100 in accordance with the principles of thepresent invention is illustrated in FIG. 1. In FIG. 1, medical devices110 are placed in a chamber 120. The chamber 120 includes a top opening121 for exhaust, a bottom opening 122 for introduction of input air 140,and at least one side wall 123. Although the chamber 120 is shown togenerally include a structure having a tapered, cylindrical shape, thechamber 120 may be of any suitable shape, such as rectangular. Thetapered configuration of the chamber 120 as shown in FIG. 1 is generallypreferred to facilitate a cyclical air flow within the chamber 120. Thecoating process of the present invention occurs within the chamber 120.

[0037] The embodiment 100 includes an air distribution plate 130, whichis secured to the side wall 123 of the chamber 120. The air distributionplate 130 has openings 131 that are smaller than the smallest dimensionof the medical devices 110 so that the medical devices 110 cannot fallthrough it. The purpose of the air distribution plate 130 is to channelinput air 140, introduced into the chamber 120 from its bottom opening122, into the coating region 150 of the chamber 120 to assist in thefluidization and coating of the medical devices 110. The airdistribution plate 130 is of any suitable shape to achieve this purpose,such as planar (as shown in FIG. 1) or concave configurations.

[0038] The air distribution plate 130 is of any suitable structure thatpermits the flow of air therethrough such as, for example, a perforatedmetal or ceramic plate or screen. Preferably, the air distribution plate130 has an open area (i.e., the planar surface area of openings) ofabout 4 to about 30 percent, such as about 4, 6, 8, 12, 16 or 30percent. A specific example of the air distribution plate 130 is astainless steel screen having an opening size of about 60 to about 325mesh. The open area and opening size of the air distribution plate 130are selected to provide for the optimum suspension and coating of themedical devices 110 within the coating region 150. For example, an airdistribution plate 130 having a large open area will result in arelatively low velocity of air within the coating region 150, and isthus used for low density medical devices 110. Conversely, an airdistribution plate 130 having a small open area will result in arelatively high velocity of air within the coating region 150, and isthus used for high density medical devices 110. The air distributionplate can be either fixed or rotating to facilitate more evendistribution of air.

[0039] The embodiment 100 further includes a nozzle 160 extendingthrough the air distribution plate 130 and into the coating region 150.The nozzle injects an air stream 161, which in this embodiment includesa coating material dispersed therein, into the coating region 150. Asshown in FIG. 1, the nozzle 160 is preferably located at or near thelongitudinal axis of the chamber 120. The embodiment 100 optionallyincludes multiple nozzles situated at various locations within thechamber 120, such as along the side 123, top, or bottom of the chamber120. In this embodiment, the nozzle 160 is used to introduce one or morecoating materials, sequentially or simultaneously, into the chamber 120.Where multiple coating materials are introduced into chamber 120, theymay be either mixed and introduced at nozzle 160, i.e., in-line mixed,or may be introduced into chamber 120 though nozzle 160 and/or from thenozzles located at the top or bottom of the chamber.

[0040] Both air streams 161 and 140 are substantially devoid ofsuspending particles, as discussed above, and the air streams mayconsist of one or more gases. Because the air streams are substantiallydevoid of any suspending particles, the surface areas of the medicaldevices to be coated when in the air stream(s) are not subject to beingobscured by, and/or damaged by contact with, the suspending particles,which could deleteriously impact the coating of the surface areas of themedical devices. In an embodiment, air stream 161 is characterized by ahigher velocity than air stream 140 that is channeled through the airdistribution plate 130 to cause a cyclical air flow and correspondingmedical device movement within the coating region 150. In other words,the high-velocity air stream 161 causes the medical devices 110 to belifted from or near the air distribution plate 130 towards the topopening 121 of the chamber 120. When the air stream 161 can no longersupport the medical devices 110, they fall through the lower-velocityair stream 140 along the sides of the chamber 120. The velocity of theair stream 140 is sufficient to slow, but not to stop or reverse, thefall of the medical devices 110. When the medical devices 110 approachor fall on the air distribution plate 130, they are again lifted by thehigh-velocity air flow 161. Thus, air streams 161 and 140 are of asufficient velocity such that the air streams themselves are able tosuspend the medical devices within the coating region. Thus, nosuspending particles are required in the air streams to suspend themedical devices to be coated.

[0041] In an embodiment where multiple nozzles are used, nozzle 160,centrally located near the air distribution plate 130 as shown in FIG.1, may be the only nozzle associated with a high-velocity air stream.Any other nozzles may be only used to inject the coating material(s)into the chamber 120 at a low velocity so as not to disrupt the cyclicalflow of air and medical devices.

[0042] An optional partition 170, which is preferably tubular in shape,may be attached to the side wall 123 of the chamber 120 and extend alongthe longitudinal axis of the chamber 120 to help facilitate the cyclicalair flow within the chamber 120 and to ensure the separation of risingand falling medical devices 110, thus minimizing potentially damaginginteractions. Also optional is a gas exhaust duct 180, which ispreferably associated with top opening 121 and which may include afilter.

[0043] In an alternative embodiment, the air streams 161 and 140 may beof substantially equal velocity. In this embodiment, the flow/velocityof the two air streams at the center of the chamber 120 would beadditive to effectively create a greater flow/velocity of air at thecenter of the chamber in comparison to the flow/velocity of the air atthe sides of the chamber, thus providing for cyclical movement of themedical devices as described above.

[0044] In yet another alternative embodiment, only one of air streams161 or 140 are utilized. For example, the airstream 161 is utilized toboth suspend the medical devices and introduce the coating material(s)into chamber 120. A cyclical flow of air within the chamber could beprovided by varying the velocity of the one air stream across it's flowpattern, such as, for example, by appropriately configuring the openingsin air distribution plate 130.

[0045] Although the embodiment 100 making use of the Wurster process isgenerally preferred for making the coated medical devices of the presentinvention, any suitable method or apparatus can be used. For example,medical devices may be loaded into a conventional fluidized bed chamber,in which air is introduced into a “bed” or layer of the medical devicesfrom below while the coating material is sprayed onto the fluidizeddevices from above. In such a process, the medical devices will moverandomly within a fluidized bed. Airless and atomized air sprayprocesses are also within the scope of the present invention. Althoughnot required by the present invention, coating within a closed chamberis generally preferred because of the corresponding ability to controlthe coating processing parameters and the chamber environment. Forexample, it is advantageous to control processing parameters such as thefluidization air composition, temperature and humidity when coating withdrugs or polymers that degrade, oxidize, hydrolyze, etc., upon exposureto specific environments. The present invention may be utilized to coatmedical devices with organic-based coating materials. Thus, operatingtemperatures in at least some embodiments of the apparatuses and methodsof the present invention are generally less than 500° C., with someembodiments having an operating temperature of between 0° C.-200° C. Theparticular operating temperatures utilized are compatible with theparticular coating materials. Thus, operating temperatures compatiblewith all of the coatings materials disclosed herein can be establishedand maintained in the apparatuses and methods of the present invention.

[0046] In other alternative embodiments of the present invention,instead of applying a coating as a preformed substance, the material ofthe coating would be generated in the spraying process. The suspendedmedical devices to be coated could be sprayed first with apolyfunctional condensation monomer followed by spraying with acomplementary condensation polyfunctional monomer to provide a polymercoating by interfacial polymerization. For example, a glycol or diaminecould be sprayed on first followed by a diisocyanate to form apolyurethane or polyurea. A potential advantage of this process would beto avoid the need for volatile solvents, application of lower viscosityfluids to improve coverage, and to provide crosslinked polymer coatingthat would be impossible to obtain by conventional coating techniques,e.g., by use of trifunctional monomers.

[0047] Other alternative embodiments for coating of the medical devicesinclude apparatuses and methods that do not involve dispensing thecoating material using an air stream through, for example, nozzle 160 asdiscussed above in connection with FIG. 1. These alternative apparatusesand methods for coating the medical devices still utilize an air streamand the structure of FIG. 1, as described above, to suspend the medicaldevices in a coating chamber; however, the medical devices could becoated by using alternative coating techniques. These alternativecoating techniques could also be utilized with the fluidized bed chambercontemplated above.

[0048] Thus, a second embodiment for an apparatus for coating medicaldevices 200 in accordance with the principles of the present inventionis illustrated in FIG. 2. The embodiment of FIG. 2 utilizes a structuresimilar to that described for the embodiment of FIG. 1, however, in theembodiment of FIG. 2, the coating material may not be dispersed withinair stream 161 by nozzle 160. In the embodiment of FIG. 2, both or oneof the air streams 161 and 140 are utilized to suspend the medicaldevices within chamber 120. A coating apparatus 210 is utilized to applythe coating to the suspended medical devices. Depending upon theparticular coating apparatus used, a coating material may be introducedinto the coating chamber by the coating apparatus itself, by one or bothof air streams 161 and 140, or through any other well-known means thatare associated with the particular coating apparatus utilized. Forreference purposes, the components for embodiment 200 in FIG. 2 that arecommon to those of embodiment 100 of FIG. 1 are designated by likereference numerals.

[0049] In the embodiment of FIG. 2, the coating apparatus 210 mayinclude a device(s) that permit the use of any number of alternativetechniques for coating the medical devices. As discussed previously, thecoating apparatus may apply a single coating or multiple coatings to themedical device. Additionally, the coating apparatus may apply coatingsto any of the different types of medical devices disclosed previously inthis specification. The apparatus may also apply any of a variety ofcoating materials as described previously.

[0050] The coating apparatus 210 may be utilized to apply one or morecoatings to medical devices by utilizing any of the following exemplarytechniques and the associated devices for these techniques forapplication of the coatings.

[0051] Ionization deposition processes can be utilized to apply coatingsto medical devices. Ionization deposition processes such as ionbeam-assisted deposition (IBAD), ion beam (IB), and ion beamimplantation (IBI). Examples of materials that can bedeposited/implanted include nitrogen, gold, silver, tungsten, titanium,aluminum, silicon, iron, nickel, selenium, tantalum, diamond-like carbon(DLC), ceramics, radioactive materials such as palladium-103, ⁶⁰Co,¹⁹²Ir, ³²P, ¹¹¹In, ⁹⁰Y, and ⁹⁹Tc.

[0052] Plasma treatment, grafting, or deposition processes can be usedto coat or modify the surface of the medical device or a part of themedical device with the following materials: monomers or oligomers,cyclic and acrylic siloxanes, silanes, silylimidazoles, fluorine-basedmonomers (hydrofluorocarbons), aliphatic and aromatic hydrocarbons,acrylic monomers, N-vinyl pyrrolidone, vinyl acetate, ethylene oxide,one or more monomers used alone or in combination in order to formblends, cross-linked polymers, copolymers and interpenetrating networkpolymers. Plasma treatment may also be used to enhance crosslinkingand/or improve surface properties such as adhesion, lubricity, orconductivity.

[0053]FIG. 3 illustrates a particular alternative embodiment for anapparatus for coating medical devices 300 in accordance with theprinciples of the present invention where the coating apparatus 210 ofFIG. 2 is a plasma coater 305. As described in connection with FIG. 2,in the embodiment of FIG. 3, both or one of the air streams 161 and 140are utilized to suspend the medical devices within chamber 120; however,a plasma coater 305 is utilized to coat the suspended medical devices.For reference purposes, the components for embodiment 300 in FIG. 3 thatare common to those of embodiments 100 and 200 of FIGS. 1 and 2,respectively, are designated by like reference numerals. Plasma coater305 includes electrodes 310, a matching network 320, and a RF (radiofrequency) generator 330. The materials to be coated on the medicaldevices may be introduced into chamber 120 through either of air streams161 and/or 140 or through any other means, such as by depositing thecoating material on air distribution plate 130 and having the airstream(s) dispense the coating material into the chamber. The coatingmaterial(s) are then applied to the medical devices by using plasmacoater 305.

[0054] In continuing with the discussion of the alternative coatingtechniques that may be utilized in the present invention, chemical vapordeposition processes are also within the scope of the present invention.Processes such as polyamide, polyimide, parylene, and parylenederivatives, polyalkylene oxide, polyalkylene glycol, polypropyleneoxide, silicone based polymers, polymers of methane, tetrafluoroethyleneor tetramethyldisiloxane or polymers from photopolymerizable monomers orcombinations thereof.

[0055] Electroplating and electrostatic deposition processes may beutilized in the present invention as well as deposition, polymerizationor treatment of part of the medical device surface or the entire devicesurface using microwave, ultra-violet light (UV), visible light, e-beam,and thermal evaporation techniques.

[0056] In any embodiment of the present invention, the apparatuses andmethods of the present invention result in the complete or partialcoating of the medical device to be coated. Partial coating isaccomplished, for example, using known masking or similar techniques toresult in the coating of predetermined struts or stent segments. Thevarious coating techniques may be used in conjunction with one anotherand, thus, they are not mutually exclusive.

[0057] In addition to the previously described coating layers and theirpurposes, in the present invention the coating layer or layers may beapplied for any of the following additional purposes or combination ofthe following purposes:

[0058] Alter surface properties such as lubricity, contact angle,hardness, or barrier properties.

[0059] Improve corrosion, humidity and/or moisture resistance.

[0060] Improve fatigue, mechanical shock, vibration, and thermalcycling.

[0061] Change/control composition at surface and/or producecompositionally graded coatings.

[0062] Apply controlled crystalline coatings.

[0063] Apply conformal pinhole free coatings.

[0064] Minimize contamination.

[0065] Change radiopacity.

[0066] Impact bio-interactions such as tissue/blood/fluid/cellcompatibility, anti-organism interactions (fungus, microbial, parasiticmicroorganisms), immune response (masking).

[0067] Control release of incorporated therapeutic agents (agents in thebase material, subsequent layers or agents applied using the abovetechniques or combinations thereof).

[0068] Or combinations of the above using single or multiple layers.

[0069] In addition to the benefits of the apparatus and methods of thepresent invention that have been discussed previously in thisspecification and in further amplification of some of the benefitsdiscussed previously, the present invention can provide the followingadvantages.

[0070] Coating in an air stream allows many medical devices or parts ofmedical devices to be coated simultaneously in batch process, whicheliminates variability that could arise if each object is coated andhandled individually.

[0071] Part to part variability is minimized because all the objects arecoated under identical conditions at the same time.

[0072] Uniformity of the coated layer, layers, or surface modificationis achieved over the entire surface of interest using careful controland optimization of the coating parameters.

[0073] In situations where the device, part of the device and/or anysubsequently coated layers contain one or more therapeutic agents, themethods yield a uniform, well-defined rate controlling membrane, or auniformly coated layer incorporating the therapeutic agents. Thisresults in uniform controlled drug release for devices, parts ofdevices, and/or coatings that contain active components.

[0074] Drug reconciliation and traceability (a critical issue infinished pharmaceutical manufacturing processes) is maximized using thistype of contained manufacturing process in situations where the device,part of the device, and/or any subsequently coated layers contain one ormore therapeutic agents.

[0075] No defects will form on the surface as a result of holding thedevice during coating since the coating is applied to the device whilethe device is levitated in the air stream.

[0076] Worker exposure to harmful chemicals, or components is minimizedbecause the process proceeds under sealed conditions.

[0077] One coater may be used to apply more than one type of coatingand/or surface modification if the equipment is designed to handlecombinations of several coating techniques such as air atomization,ionization deposition, plasma, chemical vapor deposition,electroplating, electrostatic, UV, microwave, visible, and e-beam.

[0078] The invention is further described with reference to thefollowing non-limiting examples.

EXAMPLE 1

[0079] Coronary stents are coated with a polymeric coating solution inaccordance with the present invention.

[0080] Numerous (approximately 300 to 600 in this example) NIR stents(Medinol, Tel Aviv) are placed in a Wurster fluidized bed chamber, suchas a GPCG-1 (available from Glatt Air Techniques, Ramesey, N.J.). Thestents are each about 9 mm-32 mm in length, about 1.5 mm-3.0 mm indiameter, about 7 mg-35 mg in weight, and about 46-200 mm² in surfacearea.

[0081] A coating solution of polyurethane is prepared by mixing thefollowing components (in approximate weight percentages): 0.5-1.0%Corethane 50D (Corvita, Miami, Fla.), 1.0-10.0% dimethylacetamide, andbalance tetrahydrofuran. The solution components are mixed using amagnetic stirrer for at least about 8 hours to form a solution ordispersion, which is thereafter filtered with a 1.0 micron Teflonfilter.

[0082] The stents are suspended using fluidizing air at about 2-20 psi,at a temperature of about 20-90° C. and a dew point of about 10-60° C.The stents are coated by pumping about 100-400 gm of the coatingsolution at about 0.1-6 ml/min to a nozzle located at the center of theperforated plate. The coating solution is atomized with compressedatomizing air operating at a pressure of about 2-40 psi and a flow rateof about 5 cfm. The atomizing air has a temperature of about 10-60° C.and a dew point of about 0-40° C.

[0083] Coating of the suspended stents continues until all of thecoating solution has been pumped through the nozzle. Following thecoating process, the stents are continued to be suspended for about5-180 minutes to allow for the polymer coating layer to completely dry.After drying, the stents are removed from the Wurster fluidizationchamber.

[0084] Because the stents are suspended in an air stream during thecoating process, the coated stents do not display surface defects thatnormally result when a stent is held during coating. In addition, thisis a batch process in which each stent is exposed to identical processconditions. The coating thickness depends on the size of the stent andthe amount of the coating solution applied. As a result of the goodcontrol over processing parameters during coating, the coating on eachstent strut is substantially identical.

EXAMPLE 2

[0085] Coronary stents are coated with a layer that comprises bothpolymeric and drug coating materials in accordance with the presentinvention.

[0086] NIR stents are placed in a Wurster fluidized bed chamber, asdescribed in Example 1. A coating solution is prepared by mixing thefollowing components (in approximate weight percentages): about 0.5-2.0%Elvax 40W (available from Dupont, Wilmington, Del.), about 0.05-0.6%paclitaxel, balance chloroform. The coating solution components aremixed with a magnetic stirrer for at least 8 hours to form a solution ordispersion, which is thereafter filtered with a 0.2 micron Teflonfilter.

[0087] The stents are suspended and coated by the processing parametersdescribed in Example 1. The coating process results in stents coatedwith uniform coating layers in which paclitaxel is evenly distributed oneach stent and substantially the same dose applied to every stent in thebatch.

EXAMPLE 3

[0088] Coronary stents are coated with multiple polymer coating layersin sequence distributed on each stent and the same dose applied to everystent in the batch in accordance with the present invention.

[0089] NIR stents are placed in a Wurster fluidized bed chamber, asdescribed in Example 1. A primer coating solution is prepared by mixingthe following components (in approximate weight percentages): 0.01-2%Ultrathene UE631-04 (Equistar Chemical, LP, Houston, Tex.) and 99%Chloroform. The stents are suspended and coated by the processingparameters described in Example 1. When the primer coating is completelydry, the stents are further coated with a topcoat solution comprising(in approximate weight percentages): 0.5-0.65% Corethane 50Dpolyurethane, 1.0-10.0% dimethylacetamide, and balance tetrahydrofuran,prepared by the process described in Example 1.

[0090] The coating process results in stents having uniform,dual-layered coatings. The application of the primer coating enhancesthe adhesion of the topcoat layer to the stents. In addition, byapplying several layers in sequence without removing the stents from thefluidization chamber, exposure of the stents to an outside environmentbetween layers is minimized.

EXAMPLE 4

[0091] As a variation to Example 2, a barrier layer is applied to thestents coated with a polymer/drug layer in accordance with the presentinvention. A barrier layer of ethylene vinyl acetate copolymer orsilicone protects the underlying polymer/drug layer from atmosphericdegradation such as by oxidative or hydrolytic breakdown. The barrierlayer also preferably improves abrasion resistance and durability, ormay be used to control the start or rate of release of the drug from theunderlying polymer/drug layer in vivo.

[0092] The barrier layer is the same or different composition as thepolymer in the polymer/drug layer. For example, the barrier layeroptionally comprises a dilution of MED-6605 (Nusil Silicone Technology,Carpinteria, Calif.) to 1% solids using chloroform. The hydrophobicsilicone barrier reduces the release rate from thepolyurethane/paclitaxel layer. Coating of both the barrier layer andpolymer/drug layer is preferably conducted in sequence without removingthe stents from the fluidization chamber.

[0093] The release profile of the drug may also be altered byconcurrently applying several layers of gradient concentrations to yielda multi-phasic release profile. For example, the ratio of copolymers ofpolylactic acid (“PLA”) and polyglycolic acid (“PGA”) (BirminghamPolymers, Birmingham, Ala.) containing 0.1-10% of a peptide analog suchas an analog of Somatostatin may be varied sequentially so that the drughas multiple peak release drug concentrations. For example, the initialcoated layer may comprise PLA with drug, followed by 85:15 DL-PLG withdrug, followed by 75:25 DL-PGA followed by 65:35 DL-PLG and 50:50 DL-PLGwith drug, and so on. The release rate from each layer is optionallydifferent such that the final result is several different peakscorresponding to the release from each individual layer. Layers are notlimited to a single drug.

EXAMPLE 5

[0094] The invention includes the sequential application of severallayers that contain components that are incompatible or do not share acommon solvent system. For example, an initial coating layer applied toa medical device may contain paclitaxel and corethane polyurethanecoated from solutions containing dimethylacetamide and tetrahydrofuran.A second coating layer may comprise an aqueous-based coating formulationcontaining agents that enhance surface biocompatibility such as heparinor albumin. For example, paclitaxel-PU is applied as a solution indimethyl acetamide as a first layer, followed by application of heparinand/or polyethyleneglycol in aqueous solution as a second layer. As yetanother example, benzalkonium chloride (a cationic surface-active agent)is applied as a first layer, followed by heparin (an anionicbiocompatible polysaccharide) as a second layer, thus forming an ionicbond.

[0095] The invention includes parallel applications ofdrug(1)-solvent(1) and polymer(1)-solvent(2), where the drug and polymerare soluble in different solvents or are incompatible or unstable whenpresent together. As an example, the invention is used for thesimultaneous application of aqueous solution of doxorubicinhydrochloride and silicone polymer in tetrahydrofuran from two separatefeeds, wherein the latter is used to form a drug-matrix in situ and tocontrol release kinetics. As another example, DNA solution issimultaneously applied with cationic lipid systems from two separatefeeds to eliminate shelf-life stability issues associated with DNA-lipidcomplex formulations that exhibit undesirable increases in size andturbidity as a function of salt concentration.

[0096] The invention includes parallel applications ofdrug(1)-polymer(1)-solvent(1) and drug(2)-polymer(2)-solvent(2) toeliminate compatibility or solubility issues. Examples include thesimultaneous application of (i) cisplatinhydroxypropyl methylcellulose-water and paclitaxel-PCL/PLA-chloroform from two differentfeeds; (ii) albumin or gelatin solution from one feed and gluraldehydecrosslinker from second feed; and (iii) acrylate monomer solution fromone feed and methylene bis acrylamide as crosslinker for the secondfeed.

[0097] The simultaneous coating of medical devices with incompatiblecoating materials is carried out, for example, by introducing separatefeed streams into a coating chamber via separate nozzles. When comparedto conventional coating techniques such as dip coating and spraycoating, this embodiment of the invention substantially expands thenumber of coating formulations and combinations of polymers and drugsthat may be coated onto medical devices. For example, an aqueous-basedsolution containing a desired therapeutic substance is atomizedsimultaneously with a solvent-based polymer coating solution.

EXAMPLE 6

[0098] The invention includes the coating of medical devices withcoating materials from low-viscosity aqueous or non-aqueous solutionsthat would otherwise be difficult to achieve via dip-coating or spraycoating applications. For example, peptide and protein drugs, whichoften undergo denaturation in the presence of organic solvents orexcessive heat, are easily coated onto medical devices in accordancewith the present invention. In such applications, the drug is appliedfrom an aqueous formulation and the coating process is controlled (i.e,in terms of temperature and humidity) to minimize drug degradation. Asanother example, low viscosity solutions of RGD peptides orphosphorylcholines are deposited as monolayers or as thicker coatingsfor use as drug delivery depots.

[0099] Additional Embodiments

[0100]FIG. 4 is a perspective view of an exemplary embodiment of aprotective device 40 of the present invention, which can be used toprotect at least one medical device from abrasion, scratches, etc.before, during, and/or after a coating process.

[0101]FIG. 5 is a perspective views of another exemplary embodiment of aprotective device 40 of the present invention.

[0102] Referring to FIGS. 4 and 5, medical device 410 can benon-contactably surrounded by a open-structure cage 420. In oneembodiment, such as that shown in FIG. 4, the structure of cage 420 canresemble a plurality of solid and/or hollow circular and/or ellipticalrings that are distributed about a common central point and connected toeach other at their intersections. Thus, cage 420 can be described asincluding a ring wall that defines an open structure.

[0103] In another embodiment, such as that shown in FIG. 5, thestructure of cage 420 can resemble a helical spring having alongitudinal axis and having a diameter that can bulge near thelongitudinal middle of the helix and can reduce near its longitudinalends. Thus, cage 420 can be described as including a helical wall thatdefines an open structure.

[0104] One or more securements 430 can contact (e.g., be integral to, beattached to, bear upon, etc.) cage 420 at one or more cage contactpoints 422, and can contact medical device 410 at device contact points412. Securements 430 can take various forms, including strings, strands,wires, bands, arms, and the like. For example, as shown in FIG. 4,securements 430 can be wires that are tied to medical device 410 and tocage 420. As another example, and as shown in FIG. 5, securements 430can be rubber bands that bear upon medical device 410 and cage 420.

[0105] Cage 420 and/or securements 430 can be constructed of asolvent-resistant material, such as a metal and/or an inert polymer. Forexample, cage 420 and/or securements 430 can be constructed of stainlesssteel, niconel, and/or teflon. As another example, cage 420 and/orsecurements 430 can be constructed of any appropriate base material, andcoated with a solvent-resistant and/or solvent-inert material.

[0106] In application, medical device 410 can be introduced into cage420 without directly contacting cage 420. As described above, one ormore of securements 430 can contact cage 420. There are numerousfeasible manners in which securements 430 can contact cage 420. Forexample, as shown in FIG. 4, any of securements 430 can be attached to(looped, tied, stapled, welded, and/or brazed, etc.) cage 420 at any ofseveral cage contact points 422.

[0107] In addition, one or more of securements 430 can contact medicaldevice 410. There are numerous feasible manners in which securements 430can contact medical device 410. For example, as shown in FIG. 4, any ofsecurements 430 can be attached to (looped, tied, etc.) medical device410 at any of several device contact points 412.

[0108] As another example, and as shown in FIG. 5, any of securements430 can bear against cage 420 at any of several cage contact ponts 422,and can bear against medical device 410 at any of several device contactpoints 412. In any event, cage 420 can combine with securements 430 toconstrain the movement of medical device 410 within cage 420, therebyprotecting, securing, and/or stabilizing medical device 410.

[0109] Once medical device 410 is secured within cage 420, thecombination can be suspended in an air stream that is substantiallydevoid of suspending particles. A first coating material can beintroduced into the air stream, such that at least a portion of a firstsurface of the suspended medical device is coated. Before, during,and/or after the coating process, the combination of cage 420 andsecurements 430 can protect medical device 410 from contact with othermedical devices 410, the coating chamber (not shown), and/or otherstructures that can scratch and/or damage medical device 410. When thecoating process is complete, including any needed drying, curing, etc.,medical device 410 can be removed from cage 420 and packaged forinventory and/or shipment to a medical service provider.

[0110] Because the open structure of cage 420 can be relativelylightweight, the combination of medical device 410, cage 420, andsecurements 430 can similarly be relatively lightweight. Such acombination of medical device 410, cage 420, and securements 430 can belifted, levitated, and/or suspended by the air flow present in thecoating chamber similarly to that described earlier for the medicaldevice alone. Thus, the use of this combination can enable the coatingof the medical device while effectively eliminating the likelihood ofdamage to that device and/or its coating from physical contact withother medical devices, the coating chamber, the distribution plate,and/or nozzles, etc.

[0111] The present invention provides devices and methods for protectingmedical devices during a coating process involving air suspension.Although the present invention has been described with respect toseveral exemplary embodiments, there are many other variations of theabove-described embodiments which will be apparent to those skilled inthe art, even where elements have not explicitly been designated asexemplary. It is understood that these modifications are within theteaching of the present invention, which is to be limited only by theclaims appended hereto.

[0112] For example, certain embodiments of the present invention canprotect a plurality of medical devices during a coating process. Asanother example, the protective capabilities of embodiments of thepresent invention can protect a medical device before, during, and/orafter a variety of coating processes, including drum coating and pancoating, as well as conventional coating processes such as dipping,spraying, vapor deposition, plasma polymerization, andelectrodeposition.

What is claimed is:
 1. A protective device for protecting a medicaldevice during a coating process, comprising: an open-structure cagenon-contactably surrounding a medical device, said cage having at leastone contact point; a securement in contact with said at least onecontact point and in contact with the medical device.
 2. The protectivedevice of claim 1 , wherein said cage is solvent-resistant.
 3. Theprotective device of claim 1 , wherein said securements aresolvent-resistant.
 4. The protective device of claim 1 , wherein saidcage has a plurality of contact points.
 5. The protective device ofclaim 1 , further comprising a plurality of securements in contact withsaid at least one contact point and in contact with the medical device.6. The protective device of claim 1 , wherein said cage includes a ringwall.
 7. The protective device of claim 1 , wherein said cage includes ahelical wall.
 8. The protective device of claim 1 , wherein saidsecurement is integral to said contact point.
 9. The protective deviceof claim 1 , wherein said securement is attached to said contact point.10. The protective device of claim 1 , wherein said securement bearsagainst said contact point.
 11. The protective device of claim 1 ,wherein said securement is attached to the medical device.
 12. Theprotective device of claim 1 , wherein said securement bears against themedical device.
 13. The protective device of claim 1 , wherein saidsecurement is constructed of metal.
 14. The protective device of claim 1, wherein said securement is constructed of stainless steel.
 15. Theprotective device of claim 1 , wherein said securement is constructed ofniconel.
 16. The protective device of claim 1 , wherein said securementis constructed of an inert polymer.
 17. The protective device of claim 1, wherein said securements is constructed of teflon.
 18. The protectivedevice of claim 1 , wherein said securement is coated with asolvent-resistant coating.
 19. The protective device of claim 1 ,wherein said securement is coated with a solvent-inert coating.
 20. Amethod for coating a medical device, comprising the activities of::surrounding a medical device with a cage, the medical device having asurface; securing the medical device to the cage with at least onesecurement; suspending the medical device in an air stream, the airstream substantially devoid of suspending particles; and coating atleast a portion of said surface of said suspended medical device with afirst coating material.
 21. The method of claim 20 , wherein saidactivity of coating at least a portion of said surface of said medicaldevice with a first coating material includes the activity ofintroducing said first coating material into said air stream such thatsaid first coating material is dispersed therein.
 22. A coated medicaldevice made by the method of claim 20 .
 23. A method for coating amedical device, comprising the activities of:: non-contactablysurrounding a medical device with an open-structure cage, the medicaldevice having a surface; securing the cage to a securement, thesecurement contacting the cage and the medical device; coating at leasta portion of said surface of said medical device with a first coatingmaterial.
 24. A method for protecting a medical device during a coatingprocess, comprising the activities of: non-contactably surrounding amedical device with an open-structure cage; and securing the medicaldevice to the cage with at least one securement.
 25. A method forprotecting a medical device during a coating process, comprising theactivities of: introducing a medical device into an open-structure cage;contacting the cage with a securement; contacting the medical devicewith the securement; and stabilizing the medical device within the cage.26. The method of claim 25 , wherein said medical device comprises astent.
 27. The method of claim 25 , wherein said medical devicecomprises a pre-assembly part of a catheter.
 28. The method of claim 25, wherein said medical device comprises a needle.
 29. The method ofclaim 25 , wherein said medical device comprises a blood filter.
 30. Themethod of claim 25 , wherein said medical device comprises a tissueclip.